The seized chemicals include 1 kg gunpowder, 6.5 kg sulphur, 4.8 kg lead styphnate, 1 kg beeswax, 5 litre sulphuric acid, 200 gm silica gel, 50 gm chalk powder, 100 gm putty and 500 gm liquid adhesive, said a Rab press release yesterday.

The other materials recovered are 25 yards of wire double ply, one wrench, one cutting plyer, 800 gm nuts, bolts and springs, five jugs, three funnels, six pairs of gloves, two safety pipette fillers, five thermometers, one packet pH indicator (acid-base indicator) paper, one spirit lamp, four jars, three pairs of battery plate, 2.3 kg grenade pins, eight packets of highly inflammable chemical mixed cotton, seven tap insulating rolls, 18 containers, one kg steel and iron balls, 25 switches with circuit, 203 switches without circuit, 34 plastic bodies for switch, 250 indicator bulbs and a set of balance.

The arrestees are Ashraful Islam alias Arshad alias Abbas Khan alias Araf, 22, an Ehsar [full-time activist] and commander of Sherpur upazila JMB, and Abdul Pramanik alias Mansur, 30, also an Ehsar and former commander of Mymensingh and Chittagong district units of JMB.

After a tip-off, a team of Rab-5 raided Charmathha bus terminal area in Bogra town at about 3:30pm Thursday and apprehended Ashraful.

The arrestee told Rab that a huge quantity of bomb-making materials was in the possession of Mannan. Following up the lead, the elite crime busters held Mannan in Shohagipara area in the district at about 4:30pm.

Under interrogation, Mannan admitted that he had the materials buried in North Shahpara area under Sherpur upazila. The Rab members raided the area at about 6:30pm and recovered some of the materials, digging up near a tube-well. The other explosives were found in a drum buried beside a boundary wall in the same area.

A Rab source said the seized materials are so big in quantity that they could be made into a huge number of bombs.

Ashraful, son of Moulana Abdullah Khan Salafi of Sukhdhan village under Nilphamari district, is said to have joined the militant outfit in 2003 and became an Ehsar by the end of the year, the Rab press release said. The following year he was made the commander of Sherpur JMB.

While being grilled by the law enforcers, Ashraf said JMB ranks Sherpur as a district-level zone within its organisation, considering the extent of its organisational capability in the upazila, Rab claimed. Ashraf also took part in JMB operations with its the then military commander Bangla Bhai at Baghmara in 2004.

Mannan, son of Nazmul Haq of Shohagi, used to study with JMB Majlish-e-Shura member Abdul Awal at Mohammadia Arabia Madrasa in the capital's Jatrabari area. He joined JMB in 2000 and soon became an Ehsar. The same year he graduated from being an Ehsar to taking the charge of Mymensingh district unit and the next year he was tasked with overseeing the militant activities in Chittagong.

He returned to his home district in 2003 and since then he had been using his locality as the base for running militant campaign in the region, the Rab press release read.